1. Field of the Invention
This invention relates to a positioning apparatus for use e.g. in a vending machine, which uses an optical sensor as position detecting means.
2. Prior Art
An optical sensor as position detecting means is generally formed by a light projector comprised of a light-emitting element and a light receiver comprised of a light-receiving element. The light projector and the light receiver are arranged in an opposed manner, whereby when an object intercepts a light path formed between them, a predetermined position of the object is detected. More specifically, in a case where the object for intercepting the light path is movable, and an apparatus on which the light projector and the light receiver are mounted is stationary or fixed, the movement of the object is stopped when the predetermined position of the object is detected, thus performing the positioning of the object relative to the apparatus. Conversely, when the object is stationary or fixed, and the apparatus is movable, the movement of the apparatus is stopped when a predetermined position of the apparatus is detected in a similar manner, thereby effecting positioning of the apparatus relative to the object.
As the optical sensor used in such a position-detecting device, a photointerrupter or the like is generally used, for instance. The photointerrupter is constructed as a package comprising a light-emitting element and a light-receiving element which are opposed to each other with space provided therebetween, and an electronic circuit associated with these optical elements. The photointerrupter is arranged on a fixed or stationary member, while a light-intercepting plate is provided on a movable member such that the light-intercepting plate is inserted into the space between the optical elements of the photointerrupter when the movable member is moved to a predetermined location where it should be positioned. The photointerrupter and the light-intercepting plate form the position-detecting device. In operation, the movable member moves near the fixed member until the light-intercepting plate is inserted into the space of the photointerrupter arranged on the fixed member to interrupt or cut off the light path, whereupon the electronic circuit delivers a detection signal to a drive system for driving the movable member. The detection signal causes the movable member to stop at the predetermined location where it should be positioned, thus completing positioning of the movable member relative to the fixed or stationary member.
In the case of a cup vending machine in which a cup is transferred between a body thereof including a block for preparing a drink as a vend product and a main door of same having a vend product outlet formed therein for presenting the cup containing the prepared drink to a purchaser, it is necessarily required to perform positioning of a device on the body side for delivering the cup and a device on the main door side for receiving the cup. This positioning is necessitated, because registering of the body and the main door is rather unstable due to a possible distortion of the body (cabinet) caused by the state of installation of the vending machine (when the vending machine is not placed in an exactly level position), wear of hinges of the main door, and a possible distortion of the main door itself. The positioning of the device for delivering the cup and the device for receiving the cup need be effected, though depending on the configurations of these devices, in respect of at least two of the three directions along an X-axis, a Y-axis, and a Z-axis, which are perpendicular to each other, and at the same time, it is preferred that position-detecting sensors (including switches) are of a non-contact type.
However, to effect such positioning in respect of two directions or dimensions, it is required to arrange two sets of conventional photointerrupters on one of the two devices for delivering a cup and for receiving the cup, in two respective directions perpendicular to each other such that they can determine respective positions related to the two directions perpendicular to each other, and to mount two light-intercepting plates in a manner crosswise to each other. According to this construction of an apparatus intended for positioning in respect of two directions or dimensions, however, when one of the light-intercepting plates is inserted into space in one of the two photointerrupters to effect positioning in respect of one direction or dimension, and thereafter positioning in respect of the other direction is started, the light-intercepting plate hits against the light-receiving element or light-emitting element associated therewith. This problem can be avoided, theoretically, by arranging the two optical elements of each photointerrupter such that they are opposed to each other across space for travel of a movable body (device) carrying the light-intercepting plates. In practice, however, this arrangement of the positioning apparatus gives rise to problems of scattering of light emitted from each light-emitting element and erroneous detection due to such scattering of light, so that it is required to use high-accuracy sensors in the apparatus, which makes such arrangement unsuitable for vending machines from the viewpoint of manufacturing costs, etc. In short, although the above-mentioned type of optical sensors are effective in determining a position in one direction, they are not suitable for effecting a two-dimensional positioning, i.e. putting a movable member into a predetermined position defined by parameters in two directions perpendicular to each other.